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/* Target-dependent code for GNU/Linux running on x86-64, for GDB.
Copyright 2001, 2003 Free Software Foundation, Inc.
Contributed by Jiri Smid, SuSE Labs.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include "defs.h"
#include "inferior.h"
#include "gdbcore.h"
#include "regcache.h"
#include "osabi.h"
#include "gdb_string.h"
#include "x86-64-tdep.h"
#define LINUX_SIGTRAMP_INSN0 0x48 /* mov $NNNNNNNN, %rax */
#define LINUX_SIGTRAMP_OFFSET0 0
#define LINUX_SIGTRAMP_INSN1 0x0f /* syscall */
#define LINUX_SIGTRAMP_OFFSET1 7
static const unsigned char linux_sigtramp_code[] =
{
/* mov $__NR_rt_sigreturn, %rax */
LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x0f, 0x00, 0x00, 0x00,
/* syscall */
LINUX_SIGTRAMP_INSN1, 0x05
};
#define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
/* If PC is in a sigtramp routine, return the address of the start of
the routine. Otherwise, return 0. */
static CORE_ADDR
x86_64_linux_sigtramp_start (CORE_ADDR pc)
{
unsigned char buf[LINUX_SIGTRAMP_LEN];
/* We only recognize a signal trampoline if PC is at the start of
one of the two instructions. We optimize for finding the PC at
the start, as will be the case when the trampoline is not the
first frame on the stack. We assume that in the case where the
PC is not at the start of the instruction sequence, there will be
a few trailing readable bytes on the stack. */
if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
return 0;
if (buf[0] != LINUX_SIGTRAMP_INSN0)
{
if (buf[0] != LINUX_SIGTRAMP_INSN1)
return 0;
pc -= LINUX_SIGTRAMP_OFFSET1;
if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
return 0;
}
if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)
return 0;
return pc;
}
/* Return whether PC is in a GNU/Linux sigtramp routine. */
static int
x86_64_linux_pc_in_sigtramp (CORE_ADDR pc, char *name)
{
/* If we have NAME, we can optimize the search. The trampoline is
named __restore_rt. However, it isn't dynamically exported from
the shared C library, so the trampoline may appear to be part of
the preceding function. This should always be sigaction,
__sigaction, or __libc_sigaction (all aliases to the same
function). */
if (name == NULL || strstr (name, "sigaction") != NULL)
return (x86_64_linux_sigtramp_start (pc) != 0);
return (strcmp ("__restore_rt", name) == 0);
}
/* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>. */
#define X86_64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET 40
/* Assuming NEXT_FRAME is a frame following a GNU/Linux sigtramp
routine, return the address of the associated sigcontext structure. */
static CORE_ADDR
x86_64_linux_sigcontext_addr (struct frame_info *next_frame)
{
CORE_ADDR sp;
char buf[8];
frame_unwind_register (next_frame, SP_REGNUM, buf);
sp = extract_unsigned_integer (buf, 8);
/* The sigcontext structure is part of the user context. A pointer
to the user context is passed as the third argument to the signal
handler, i.e. in %rdx. Unfortunately %rdx isn't preserved across
function calls so we can't use it. Fortunately the user context
is part of the signal frame and the unwound %rsp directly points
at it. */
return sp + X86_64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
}
static void
x86_64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
x86_64_init_abi (info, gdbarch);
set_gdbarch_pc_in_sigtramp (gdbarch, x86_64_linux_pc_in_sigtramp);
tdep->sigcontext_addr = x86_64_linux_sigcontext_addr;
tdep->sc_pc_offset = 16 * 8; /* From <asm/sigcontext.h>. */
tdep->sc_sp_offset = 15 * 8;
}
/* Provide a prototype to silence -Wmissing-prototypes. */
extern void _initialize_x86_64_linux_tdep (void);
void
_initialize_x86_64_linux_tdep (void)
{
gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64, GDB_OSABI_LINUX,
x86_64_linux_init_abi);
}
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